Light Emitting Diodes (LEDs) and Amplified LEDs (ALEDs) have recently become very important for use as transceivers in local access systems. Illustrative applications of the use of LEDs and LEDs in transceivers is described in our recently filed U.S. patent application C. R. Doerr, K -Y Liou and B. Glance, case 11 - 46 - 12, Ser. No. 08/857,347, filed on May 16, 1997 and entitled FULL-DUPLEX WAVELENGTH DIVISION MULTIPLEXING SYSTEM USING SINGLE-DEVICE TRANSCEIVERS, pending. That application describes the use of LEDs and ALEDs as transceivers at both the Central Office (CO) and Remote Node (RN) locations of a single-fiber full-duplex WDM system. In such typical applications, the temperature at the CO location is usually controlled while the temperature at the RN location is uncontrolled and can vary drastically. As a result, at the RN location the optical power from an LED/ALED varies substantially with temperature changes which, undesirably, may cause LED/ALED laser operation (at low temperatures) or reduced signal to noise levels (at higher temperatures). Consequently, a problem exists at the RN location to maintain a nearly constant optical output from an LED/ALED transceiver over the expected temperature range.
In the prior art, a circuit for the regulation of the power output of a laser or LED transmitter typically uses a photodiode to monitor power levels. The detected optical power level from the photodiode is then used by a feedback control circuit to regulate the power level of the laser or LED. Undesirably, such active power regulators are complex and expensive.